A two and a half years postdoctoral position in atmospheric science
is available at Ecole Normale Supérieure in Paris, to work on the
spatial organization of deep convective clouds in the tropics. Problems
of particular interest are i) what are the physical processes
responsible for the spatial organization of deep clouds in the tropics,
and ii) what implications for tropical cyclogenesis, in our current and
in a warming climate. Please click HERE for more information.

OVERALL RESEARCH INTERESTS

My research interests lie in the
fields of geophysical fluid dynamics and climate science. I am
particularly interested in the study of processes which are too small
in space and time to be explicitly resolved in coarse-resolution
General Circulation Models (GCMs) used for climate prediction.

Important examples that I work on are internal wave breaking in
the ocean and cloud processes in the atmosphere. These subgrid-scale
processes need to be parametrized in GCMs in order to improve current
model projections of climate change.

THE HYDROLOGICAL CYCLE AND CLIMATE CHANGE

Precipitation extremes, both wet
(floods) and dry (deserts), have many societal impacts. I investigate
how precipitation extremes respond to warming using a cloud-resolving
model (see Publications for more details).

The figure below shows a snapshot from the cloud-resolving model. The
colors represent the surface temperature, and the white contours are
isosurfaces of condensate amounts (liquid and ice). Understanding the
response of the hydrological cycle to climate change is a major
challenge, and the subject of intense research.

Snapshot from a cloud-resolving simulation (click on it for a movie)

THE ORGANIZATION OF CONVECTION IN HIGH-RESOLUTION SIMULATIONS

Tropical
convection
can organize on a wide range of scales, but the physical processes
behind this organization are still unclear. Several studies using
high-resolution cloud-resolving models point out the tendency of
atmospheric convection to self-aggregate when the domain is large
enough. This self-aggregated state is a spatially organized atmosphere
composed of two large areas: a moist area with intense convection, and
a dry area with strong radiative cooling. I used a cloud-resolving
model to investigate in detail the onset of self-aggregation (see
Publications for more details).

The figure below shows a snapshot from the cloud-resolving model. The
small-domain run (top panel) has reached radiative convective
equilibrium. The large-domain run (bottom panel) looks quite different;
convection spontaneously aggregates, eventually leading to an
atmospheric state with one convectively active moist region surrounded
by very dry air.

Self-aggregation on large domains (click on it for a movie)

THE DISSIPATION OF INTERNAL TIDES AND THE OCEANIC CIRCULATION

Internal tides are internal waves generated by the interaction of tidal
currents with deep-ocean topography. Their dissipation through wave
breaking and concomitant three-dimensional turbulence contributes to
vertical mixing in the deep ocean, and hence could play a role in the
large-scale ocean circulation.

I investigate the instability and dissipation of the internal tides,
and the induced abyssal mixing (see Publications for more details).